An adsorbent fractionator is an apparatus that receives a mixture of two or more gases and separates part or all of one of these gases from the mixture by passing the gas mixture over an adsorbent bed. One type of adsorbent fractionator, or desiccant dryer, configures two vertical desiccant tanks to alternately receive an influent gas with moisture from a common inlet source. The influent gas mixture is cyclically routed through one desiccant tank during one adsorption cycle, and then through the second desiccant tank for one adsorption cycle. During portions of this cycle, a fraction of the effluent gas from the tank currently in the adsorption cycle is rerouted through the opposite tank in the reverse direction in order to regenerate the desiccant bed. Thus, a series of valves are required to control the direction and flow of the influent adsorption cycle gas mixture and the effluent regeneration cycle gas.
In certain desiccant dryers, a series of inlet valves receives from an inlet source an influent gas with moisture to be removed, and routes that gas mixture to the desiccant tank currently in the adsorption cycle. Simultaneously, a series of exhaust valves receives the effluent gas from the opposite desiccant tank, which is in the regeneration cycle, and routes the effluent gas through an exhaust port and eventually to the atmosphere. Thus, at any given time, one of the two inlet valves is open, allowing the influent gas to pass through to one of the two desiccant tanks. In addition, one of the two exhaust valves may also be open to allow effluent gas to exhaust to the atmosphere after passing through the opposite desiccant tank in the reverse direction.
In certain desiccant dryers, a series of purge inlet valves receives gas from a purge inlet source and routes that gas mixture to the desiccant tank currently in the regeneration cycle. Simultaneously, a series of outlet valves receives the effluent gas from the opposite desiccant tank, which is in the adsorption cycle, and routes the dried effluent gas out of the dryer. Thus, at any given time, one of the two outlet valves is open to allow process effluent gas to flow downstream after passing through one of the two desiccant tanks. In addition, one of the two purge inlet valves may be open, allowing the purge gas to pass through to the opposite desiccant tank in the reverse direction.
While the foregoing systems are useful, improvements are still desirable. For example, the existing systems can require a multiplicity of valve assemblies, or multiple valve bodies to hold multiple valves, to control the direction and flow of the gases. The existing systems also are limited to some extent by their method of manufacture, which involves multiple machining and assembly steps, resulting in relatively high production costs and a heavier product than is desirable. Furthermore, machining limitations may result in the existing systems having a less aerodynamically efficient internal flow path than desired.
Accordingly, it is desirable to provide a directional flow control valve assembly with a reduced number of pieces that is able to accept one or more identical valves for use in an adsorbent fractionator. It also is desirable that the valve assembly be lighter in weight and have an aerodynamically efficient internal flow path. Furthermore, it is desirable to have a valve body that is easy and less costly to manufacture.